1. Technical Field
This invention relates to a photographic apparatus and a method suitable for use in a digital camera for taking still images or a video camera for moving images and, particularly relates to a photographic apparatus having a function to output a lens distortion corrected image taken with a CCD (charge-coupled device) camera, a monitoring camera or the like and relates to a method thereof.
2. Related Arts
Conventionally, images photographed with a digital camera for taking still images or a video camera for taking moving images have been generally printed on sensitive papers or displayed on monitoring screens as they are, particularly, without correction of image distortion due to a fish-eye lens or wide-angle lens, for example. The fish-eye lens and wide-angle lens are suitable to the field in which the width of a field of view is given preference over the image distortion, such as a monitoring camera. To take a landscape or scene, a plurality of photos arranged side-by-side to form so-called a panoramic photo have been taken. Also, there has been a camera to make an image suitable to an object by adjusting the focal length of the camera with the use of its zoom function to adjust the field of view of one image.
On the other hand, if it is intended to take a photographed image without image distortion due to a lens distortion then a camera having a high-precision lens, for example a camera for aerial photogrammetry, is available. However, such a camera having a high-precision lens is expensive. It is therefore a problem that such a camera is difficult to be used in the application for which an equipment budget is limited. It is also proposed to correct the image distortion due to the lens distortion. However, it is another problem that perfect correction of the image distortion is difficult in case of complex variation of the image distortion such as in a zoom lens or fish-eye lens.
When a wide-angle lens or a fish-eye lens is used in a monitoring camera, the image distortion increases, particularly at the peripheral area of the image. If a clear image is required to identify, for example fire causes of buildings or thieves and robberies, it is yet another problem that examination from the image without correction of its distortion is difficult to perform. For the panoramic photos, the distortion occurred at its peripheral area is also a problem when adjoining photos are jointed together. Further, a camera with a zoom function has a problem that the image distortion is larger than that of a fixed focus length camera because the lens distortion is changed in response to the adjusted focal length.
This invention solves the problems described above and the object of the invention is to provide a photographic apparatus with an image correction function and a method thereof, in which even an image obtained with for example a wide-angle lens or an eye-fish lens has a large distortion at its peripheral area, the lens distortion is suitably corrected and the image distortion is small in spite of the image having a wide field of view. It is also another object of the invention to provide a photographic apparatus with an image correction function and a method thereof, in which the lens distortion is suitably corrected and the image distortion is small at the junction of the adjoining images when the adjoining images are jointed to form an image having a wide field of view, such as a panoramic photo. It is yet another object of the invention to provide a photographic apparatus with an image correction function and a method thereof, in which an image is always suitably corrected even in a moving picture camera with a zoom function.